oh no, white spots!!!

Im an eighteen year old female with very fair skin and ive had a long history of acne problems. i was on accutane last year and the problem is now minimal. but a few weeks ago i noticed that i had a few white spots on my cheeks where it looked like i had lost all pigmentation. they were very small, less than 1/4 inch and perfecly circular. i watched them and they went away. i have recently spent a lot of time out in the sun and noticed today that the spots are back. i have about four or so on each cheek. like i said they are very small, but i am really freaked out none the less. can anyone tell me what this is? should i not worry or call up my dermatologist? i would really love any ideas so i can look it up and figure out what is going on

Sometimes medication can do these sorts of things. I would call the derm. and see what he suggests. It could also be the start of vitiligo, something you should start treatment on right away. I would'nt worry yet,being they went away once. It does'nt sound like vitiligo because that does'nt go away.